--ARRRRGH ACCIDENTALLY CLOSED A WINDOW AND LOST EVERYTHING

Don't Starve, Fez, Kerbal Space Program, Factorio are things I listed and I don't feel like retyping.

You can get Costume Quest, Psychonauts, and stacking for $1 (with steam codes) on the humble bundle.

Otherwise Garry's mod, OpenTTD, and emulators have already been suggested.

single player terraria.